Grails MappingException: Missing type or column for column

I've been trying to upgrade an older project from grails 2.3.9 to grails 2.4.4.
I've done this sort of upgrade with many of my other projects without issues, but this time around I got stumped on the following error:

 MappingException: Missing type or column for column

The error message was not particularly helpful, since I know the domain class mapping was correct in a previous version of Grails. The way associations between domain classes, hasn't changed. So find the underlying cause wasn't easy and I wanted to share it with you in case you run into a similar problem.

 In my domain classes there many getters methods that had no corresponding field defined. For example, I had a getter called, getFoo()  but there was no corresponding field in the domain class called 'foo'. When using such getter methods in Grails, normally we should define a static list of transients as follows:

static transients = ['foo']

Once these transients were defined, then the error messages stopped